Breckenridge Tunnel SIPP

Michels Trenchless, Inc. rehabilitated a combined sewer pipe by hand spraying 259 linear feet of geopolymer lining in a 56-inch concrete tunnel sewer to a thickness of 1-3/4 inches; 1,122 linear feet of geopolymer lining in a 72-inch concrete tunnel sewer to a thickness of 2 1/4 inches; 130 linear feet of geopolymer lining in a plated tunnel sewer to a thickness of 3 inches; 50 vertical feet of geopolymer lining in a manhole shaft; and approximately 325 linear feet of geopolymer fill in the belly of the pipe.

Maintaining a bypass system was challenging with a combined system that filled quickly with any rain. This issue was compounded working during a season that included about a dozen days of rain. Because individual workers were mechanically lowered 50 feet down a 24-inch-diameter manhole into the sewer tunnel, extreme caution was taken to return them to street level as soon as rain started. After the crew was extracted, the plugs were removed to allow wastewater to flow through the pipe.

The crew completed work with access points located 1,200 linear feet from one another.